JPH0741132B2 - Circulating water circuit for electronic parts processing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a circulating water circuit for processing electronic parts, which is used to advantageously circulate high-purity water used for processing electronic parts.

[Conventional technology]

In the cutting and polishing of electronic parts and elements, recently, extremely precise processing accuracy of ± 0.05 μm has been required. Cleaning water is generally used in such precision processing steps, but strict temperature control and purity control are also required for this cleaning water. The primary goal is to keep the temperature within ± 0.5 ° C and to maintain the purity of fine particles of 1 μm or more.

A large amount of fine particles are contained in the washing water that has undergone the processing process. Therefore, when draining this water, it is necessary to remove these fine particles from the viewpoint of pollution, and when it is recycled and used again. I have to. The most commonly used method for removing fine particles has been filtration separation.

[Problems to be solved by the invention]

In terms of temperature, the wash water that has passed through the processing process containing a large amount of fine particles is close to the required temperature, so recycling this will achieve a thermal economy, and in terms of saving water. Be advantageous. However, when fine particles are captured by using the most advanced conventional filter, for example, a 0.5 μm-cut cotton filter, clogging occurs immediately. Therefore, it is conceivable to install filters with different sieves in multiple stages and capture the larger diameters in order from the upstream side to the downstream side, but the pressure loss increases and a large pump power is required. In any case, it is necessary to change the filters frequently, and there is a problem that maintenance is negligible.

Also, it is beneficial to add a coagulant in order to improve the collection efficiency of fine particles, but the use of a coagulant contaminates the cleaning water itself, which is a problem in circulating this in the precision machining process of electronic parts. is there.

[Means for solving problems]

The present invention has been made for the purpose of solving the above-mentioned problems, and a water circulation path for circulating water used in the cutting or polishing process of electronic parts and elements to the process again has a high gradient from the upstream side. It is intended to provide a circulating water circuit for processing electronic parts, which is equipped with a magnetic separator, a filter, and a water temperature controller so that water can be passed through these devices without adding a flocculant.

As is well known in principle, the high gradient magnetic separator used in the present invention is a magnetic medium (matrix) having an extremely small radius of curvature in a uniform magnetic field between magnetic poles.
By inserting, a local magnetic field density is formed near the surface of the part with a small radius of curvature, and a large magnetic field gradient is generated. As this matrix, spiral wire, mesh,
A corrugated sheet laminate having irregularities is used. Then, the liquid to be treated is passed through a water-permeable matrix placed between the magnetic poles, whereby magnetic particles in the liquid to be treated are magnetically adhered to this matrix.

The inventors of the present invention have found that, when water for processing and cleaning electronic components and elements is passed through such a high gradient magnetic separator, magnetic particles as well as fine non-magnetic particles can be obtained without using an aggregating agent. It was found that most of them can be separated and removed by this high gradient magnetic separator.

As the type of high gradient magnetic separator, a fixed type, a rotary type and a reciprocating type are known, and any type can be used in the present invention, but the reciprocating type is particularly preferable. This is to reciprocate a matrix between fixed magnetic poles. Specifically, a trough having an elongated upper and lower surface opening in which the matrix is loaded reciprocates between an N pole and an S pole which are arranged opposite to each other. Then, the liquid to be treated is vertically passed through the matrix between the magnetic poles, and the high pressure water for washing out the magnetic substance is vertically passed through the matrix apart from the magnetic poles. according to this,
The matrix from which the magnetic substance has been washed out always moves back and forth between the magnetic poles, and the liquid to be treated comes into contact with it, enabling efficient continuous treatment. The fixed type has a fixed magnetic pole and matrix, and switches the flow of the liquid to be treated and the washing water, and the rotary type rotates a ring-shaped matrix between the fixed magnetic poles.

In the present invention, a filter is installed after this high gradient magnetic separator. This is a high performance filter, eg 0.5 μm
Use a cut cotton filter. At the stage of passing through the high-gradient magnetic separator, most of non-magnetic particles including magnetic particles are removed, but some of the non-magnetic particles are removed in the water after passing through the high-gradient magnetic separator. Will accompany you. In the present invention, this small amount of fine particles is removed by using a high performance filter.

The temperature of the circulating water from which the fine particles have been removed is adjusted next. If there is an extra heat source in the processing plant, a heat exchanger that uses the heat is used as the temperature control device, and a heater is used to adjust the final temperature. In the present invention, since the temperature-controlled water that has entered the working process is returned to the working process again, the heat applied to the circulating water is only the amount of heat radiated in the circulating path, and compared with the case of using new water. The capacity of the temperature control device can be small.

The following is an example of the circulating use of processing cleaning water for the VTR head.

Cooling water (washing water) in the VTR head machining process that achieves a control resolution of 0.1 μm and a stroke of 100 mm with an accuracy of 1 μm or less must be temperature-controlled within a fluctuation range of ± 0.5 ° C, 1 μm Should not contain any of the above particles. After processing, the cutting water of the work (Mn, Zn ferrite), the cutting powder from the work table (made of carbon), the diamond abrasive grains peeled from the blade, the powder of the instant adhesive, etc. are mixed in the cleaning water after processing. Therefore, when this wash water is circulated and used, it must be filtered so that particles of 1 μm or less are not contained.

FIG. 1 is a process diagram of a comparative example in which the cooling cutting water of the VTR head is circulated and used, and FIG. 2 is a process diagram of an example of the present invention.

In the comparative example shown in FIG. 1, the cleaning water 1 from the VTR processing step is collected in the first tank 2 and the pipe 5 for supplying water to the second tank 4 by the pump 3 can capture particles having a size of 5 μm or more. Coarse cotton filter 6 and 0.5 μm downstream
A high-performance cotton filter 7 capable of capturing the above particles is interposed in series, and the water collected in the second tank 4 is pumped by a pump 8 through a heat exchanger 9 and a heater 10.
This is an example of returning to the VTR processing step after controlling the temperature within a fluctuation range of 0.5 ° C. The particle concentration of cleaning water 1 (particle concentration in the first tank) discharged from the VTR processing step was in the range of 1.3 to 3.6 ppm, and was 2.6 ppm on average. Filter 6 at the start of circulation
The differential pressure of each and the differential pressure of the filter 7 are 0.35kgf / cm
² , which was 0.7 kgf / cm ² in total, but immediately clogged. When the differential pressure of the filter 6 and the differential pressure of the filter 7 in the clogging state immediately before replacement were measured,
2.5kgf / cm ² and 2.2kgf / cm ² , respectively, total 4.7kgf / c
It was m ² .

FIG. 2 is an example of the present invention which is substantially the same as the process of FIG. 1 except that the coarse cotton filter 6 is removed from the process of FIG. 1 and the high gradient magnetic separator 11 is inserted in the path of the washing water 1. Is shown. A reciprocating type was used as the high gradient magnetic separator 11. This is to reciprocate the trough 15 loaded with the matrix 14 in the uniform magnetic field formed by the magnetic pole 13 (gap in which the N pole and the S pole are opposed to each other). On the other hand, the wash water 1 is passed through, and after passing through the matrix 14, the water is collected in the first tank 2. On the other hand, high-pressure water is supplied from the nozzles 16 and 17 to the matrix 14 that has exited the magnetic pole 13 by the reciprocating motion, the substances adhering to the matrix 14 are washed out, and the washed water is collected in the tank 18. The matrix 14 has a wire diameter of 1.
A 0 mm SUS410 stainless steel wire is used with a filling rate of 13.
The trough 15 was loaded with 2% and a thickness of 15 cm in the flow direction. Magnetic pole 1
Externally applied magnetic field at 3 is 2KOe, washing water to matrix 14 is 1
The average filtration flow rate was 10 cm / s or less, and the washing water from the processing step having the same concentration as in the comparative example of FIG. 1 was treated.

As a result, the concentration of fine particles in the water before being processed by the high gradient magnetic separator 11 was 1.3 to 3.6 ppm, but was 0.2 to 0.6 ppm after the treatment. The capture efficiency for fine particles was 82%. Further, as a result of analyzing the particles removed by the high gradient magnetic separator 11 (particles in the collected water in the tank 18), 70% of magnetic particles (ferrite component) and the remaining 30% were non-magnetic particles. That is, most of the non-magnetic particles were also caught in the magnetic particles and removed by the high gradient magnetic separator 11. Also high gradient magnetic separator
The size of the particles removed in 11 was in the range of 0.1 to 8 μm, and the weight-based 50% average diameter was 0.27 μm. The processing time until the 0.5 μm-cut cotton filter 7 was clogged was about 10 times longer than that in the comparative example of FIG. The total capture efficiency was 85% or less in the comparative example, but was 97% or more in the inventive example.

[Brief description of drawings]

FIG. 1 is a process diagram showing a comparative example in which the cleaning water discharged from the VTR processing process is circulated and used, and FIG. 2 is a process diagram showing an example of the present invention in which the same cleaning water is circulated and used. 1 …… Wash water from VTR processing process, 2 …… First water collection tank, 6 …… 5μm cut filter, 7 …… 0.5μm cut filter, 9 …… Heat exchanger, 10 …… Heater, 11… … Reciprocating high gradient magnetic separator, 13 …… Magnetic pole, 14 …… Magnetic medium (matrix), 15 …… Trough, 16,17 …… High pressure water nozzle for washing out.

Claims (2)

[Claims] 1. A circulating water circuit for processing electronic parts, wherein water containing magnetic fine particles and non-magnetic fine particles used in a cutting or polishing step of electronic parts or elements is circulated again in the step,
A water-permeable high-gradient magnetic separator in which a magnetic medium having a large number of surface portions having a small radius of curvature is arranged between magnetic poles to form local magnetic field density near the surface is provided in the circuit. A circulating water circuit for processing electronic parts, which is installed and returns the water in which most of the magnetic fine particles and most of the non-magnetic fine particles are separated by this high gradient magnetic separator to the process through a filter and a water temperature regulator. . 2. The circulating water circuit for processing electronic parts according to claim 1, wherein the circulating water is passed through a high gradient magnetic separator and a filter without adding a flocculant.